PHP string Encryption Decryption Program example

The most common applications are in user login and some API data exchange scenarios.
The author contains some of the more classic PHP encryption and decryption function code, to share with you. Encryption and decryption principle is generally through a certain encryption and decryption algorithm, the key into the algorithm, the end of the encryption and decryption results.
1, very authcode encryption function, discuz! Classic code (with detailed):

The code is as follows

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function Authcode ($string, $operation = ' DECODE ', $key = ', $expiry = 0) { Dynamic key length, the same plaintext will generate different ciphertext is depending on the dynamic key $ckey _length = 4; Secret Spoon $key = MD5 ($key $key: $GLOBALS [' Discuz_auth_key ']); Key A will participate in encryption and decryption $keya = MD5 (substr ($key, 0, 16)); Key B is used for data integrity verification. $KEYB = MD5 (substr ($key, 16, 16)); Key C used to change the generated ciphertext $KEYC = $ckey _length? ($operation = = ' DECODE ' substr ($string, 0, $ckey _length): SUBSTR (MD5 (Microtime ()),-$ckey _length)): '; Keys for participating operations $cryptkey = $keya. MD5 ($keya. $KEYC); $key _length = strlen ($cryptkey); Clear text, the first 10 bits are used to hold the timestamp, verify the validity of the data when decrypting, 10 to 26 bits to save the $KEYB (key B), Data integrity is validated through this key during decryption If it is decoded, it will start from the $ckey_length bit, because the ciphertext before the $ckey_length bit to save the dynamic key to ensure that the decryption is correct $string = $operation = = ' DECODE '? Base64_decode (substr ($string, $ckey _length)): sprintf ('%010d ', $expiry? $expiry + Time (): 0). substr (MD5 ($string. $keyb), 0). $string; $string _length = strlen ($string); $result = '; $box = Range (0, 255); $rndkey = Array (); Create a key book for ($i = 0; $i <= 255; $i + +) { $rndkey [$i] = Ord ($cryptkey [$i% $key _length]); } Using a fixed algorithm to disrupt the key book, increase the randomness, seems very complex, in fact, will not increase the intensity of the ciphertext for ($j = $i = 0; $i < 256; $i + +) { $j = ($j + $box [$i] + $rndkey [$i])% 256; $tmp = $box [$i]; $box [$i] = $box [$j]; $box [$j] = $tmp; } Core Plus decryption section for ($a = $j = $i = 0; $i < $string _length; $i + +) { $a = ($a + 1)% 256; $j = ($j + $box [$a])% 256; $tmp = $box [$a]; $box [$a] = $box [$j]; $box [$j] = $tmp; To derive a key from a key book, or to convert it to a character. $result. = Chr (ord ($string [$i]) ^ ($box [($box [$a] + $box [$j])% 256]); } if ($operation = = ' DECODE ') { Verify data validation, see the format of unencrypted plaintext if (substr ($result, 0,) = 0 | | substr ($result, 0)-time () > 0) && substr ($result) = = substr (MD5 (substr ($result,). $keyb), 0, 16)) { Return substr ($result, 26); } else { Return "; } } else { Keep the dynamic key in the ciphertext, which is why the same clear text can be decrypted after producing a different cipher. Because the encrypted ciphertext may be some special characters, the copy process may be lost, so use base64 encoding Return $KEYC. Str_replace (' = ', ', Base64_encode ($result)); } }

$string in function Authcode ($string, $operation, $key, $expiry): string, plaintext, or ciphertext; $operation: decode means decryption, other means encryption; $key: Key; $ Expiry: The validity of redaction.
Usage:

The code is as follows	Copy Code
$str = ' abcdef '; $key = ' www.111cn.net '; Echo Authcode ($str, ' ENCODE ', $key, 0); Encryption $str = ' 56f4yer1di2wtzwmqsfpps9hwyojnfp2mpc8sohrrxo7bok '; Echo Authcode ($str, ' DECODE ', $key, 0); Decrypt

2, add the decryption function encrypt ():

The code is as follows

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function Encrypt ($string, $operation, $key = ') { $key =md5 ($key); $key _length=strlen ($key); $string = $operation = = ' D ' Base64_decode ($string): substr (MD5 ($string. $key), 0,8). $string; $string _length=strlen ($string); $rndkey = $box =array (); $result = '; For ($i =0 $i <=255; $i + +) { $rndkey [$i]=ord ($key [$i $key _length]); $box [$i]= $i; } for ($j = $i =0; $i <256; $i + +) { $j = ($j + $box [$i]+ $rndkey [$i])%256; $tmp = $box [$i]; $box [$i]= $box [$j]; $box [$j]= $tmp; } for ($a = $j = $i =0; $i < $string _length; $i + +) { $a = ($a + 1)%256; $j = ($j + $box [$a])%256; $tmp = $box [$a]; $box [$a]= $box [$j]; $box [$j]= $tmp; $result. =CHR (Ord ($string [$i]) ^ ($box [($box [$a]+ $box [$j])%256]); } if ($operation = = ' D ') { if (substr ($result, 0,8) ==substr (MD5 (substr ($result, 8). $key), 0,8)) { Return substr ($result, 8); }else{ Return "; } }else{ return str_replace (' = ', ', ' Base64_encode ($result)); } }

function Encrypt ($string, $operation, $key) in $string: Need to encrypt the decrypted string, $operation: The judge is encrypted or decrypted, E is encrypted, d is decryption; $key: Key.
Usage:

The code is as follows	Copy Code
$STR = ' abc '; $key = ' www.111cn.net '; $token = Encrypt ($str, ' E ', $key); Echo ' encrypt: '. Encrypt ($str, ' E ', $key); Echo ' Decrypt: '. Encrypt ($str, ' D ', $key);